In reply to Removed UserAvaunt:
I've worn a down vest in combintation with my synthetic ME Fitzroy jacket. Both underneath and over the top!
It's a great booster layer in cold conditions.
Specifically, I will put it underneath in damper comditions but I have wondered if this has compressed the down too much to make it worthwhile. Though putting it over the top I also wonder if any body heat gets through the synthetic jacket to warm the down up...?!
It's worth experimenting with anyway and I always find the two layers are much more versatile then one big heavy jacket.
Hope that helps?